U.S. patent number 11,040,422 [Application Number 16/350,853] was granted by the patent office on 2021-06-22 for manual stage with magnetic sensor and digital readout.
The grantee listed for this patent is Dennis Willard Davis, James Wallin. Invention is credited to Dennis Willard Davis, James Wallin.
United States Patent |
11,040,422 |
Davis , et al. |
June 22, 2021 |
Manual stage with magnetic sensor and digital readout
Abstract
The disclosed device comprises a manually-actuated micro
positioning stage that incorporates a mechanism for measurement and
electronic output of the stage slider position. A Hall Effect
sensor device is used to sense rotary position of the lead screw.
based on the lead screw pitch. Processor means converts the Hall
Effect sensor measurement of the lead screw rotational displacement
into linear displacement of the stage slider for presentation on an
electronic display. A magnetically-permeable cap contains a small
disc magnet that is poled diametrically and is affixed to the end
of the lead screw that is in contact with the stage slider by means
of a sensor housing. The Hall Effect sensor contained in a surface
mount electronic package is enclosed in a sensor housing that is
part of the stage slider that is in contact with the lead screw and
is positioned coaxially with the lead screw.
Inventors: |
Davis; Dennis Willard (Palm
Bay, FL), Wallin; James (Terra Ceia, FL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Davis; Dennis Willard
Wallin; James |
Palm Bay
Terra Ceia |
FL
FL |
US
US |
|
|
Family
ID: |
1000003911302 |
Appl.
No.: |
16/350,853 |
Filed: |
January 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62709654 |
Jan 25, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01D
5/145 (20130101); G01B 5/0002 (20130101); B23Q
1/44 (20130101); B23Q 1/0054 (20130101); B23Q
1/262 (20130101); G01B 7/30 (20130101); G01D
11/245 (20130101) |
Current International
Class: |
B23Q
1/26 (20060101); G01D 11/24 (20060101); G01B
5/00 (20060101); B23Q 1/44 (20060101); G01D
5/14 (20060101); G01B 7/30 (20060101); B23Q
1/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Patel; Nimeshkumar D
Assistant Examiner: Courson; Tania
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of provisional patent
application Ser. No. 62/709,654 filed 2018 Jan. 25.
Claims
The invention claimed is:
1. A manually-actuated linear stage with digital display
comprising: a. a stage body serving to provide the support
structure for the stage, b. slider rails upon which the slider
travels under lateral preload, c. a slider, d. a
manually-adjustable lead screw of determined pitch, exhibiting an
axis of rotation, threaded into the stage body and in contact with
the slider, e. a return spring serving to preload the slider
against the lead screw along the rotational axis of the lead screw,
f. a magnet exhibiting a circumferentially inhomogeneous magnetic
field affixed to the lead screw in proximity to the lead screw
contact with the slider, g. a magnetic sensor affixed to the slider
in proximity to the lead screw contact with the slider, h.
processor and display means, i. communication means providing
signal communication between the magnetic sensor and the processor
and display means, wherein rotation of the lead screw advances the
slider and causes concurrent rotation of the magnet affixed to the
lead screw and the magnet's circumferentially inhomogeneous
magnetic field, the change in magnetic field strength sensed by the
magnetic sensor located on the slider is a measure of the
instantaneous angle of rotation of the lead screw and is
communicated via communication means to the processor and display
means, based on the measured angular motion and pitch of the lead
screw, the processor calculates a value for the resulting
longitudinal position of the slider and provides this information
to the display means.
2. A manually-actuated linear stage with digital display as recited
in claim 1 wherein the communication means comprises a wired
electrical connection.
3. A manually-actuated linear stage with digital display as recited
in claim 1 wherein the communication means comprises a wireless
connection.
4. A manually-actuated linear stage with digital display as recited
in claim 1 wherein the processor means permits switching the
display between metric and English units.
5. A manually-actuated linear stage with digital display as recited
in claim 1 wherein the processor means calculates permits setting
the current, measured slider position to zero.
6. A manually-actuated linear stage with digital display as recited
in claim 1 wherein the processor means stores slider position for
recall in the event of power loss.
Description
BACKGROUND
Compact, manual, lead screw-driven positioning stages are available
that offer micro-positioning capability based on use of
axially-preloaded precision lead screws and laterally-preloaded
sliders. Although such stages provide submicron adjustment
sensitivities, measurement of actual slider translation must be
accomplished by attached micrometers or external measurement
devices. Attached micrometers are not accurate enough to measure
the finest motion available from these stages. Also, both
micrometers and external measurement devices consume space that
detracts from the compact size of the stage, which is critical to
many applications. What is needed is a stage-integrated sensor that
can provide the necessary accuracy in a small volume.
SUMMARY OF THE INVENTION
Disclosed is a compact manual stage that uses a lead screw to drive
an axial spring-preloaded slider which incorporates a sensor that
measures rotation of the lead screw. The sensor comprises a device
that measures the motion of a rotating inhomogeneous magnetic field
associated with a magnet mounted on the end of the lead screw. The
sensor is mounted on the moving slider and a flexible circuit
electrically connects the sensor to a connector port on the
non-moving stage body. The connector port permits a wired
connection between the stage and display enclosure that provides
sensor power, processes the sensor output and displays the real
time position measurement of the stage slider on a dedicated
display. An alternate embodiment of the disclosed device exploits a
battery-powered sensor and a wireless connection between the
sensor/stage and a remote processor and display.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial diagram of a prior art manual micro
positioning stage.
FIG. 2 is a pictorial diagram of a micro positioning stage
incorporating means to electronically display slider position.
FIG. 3 is a bottom pictorial diagram of the stage of FIG. 2
depicting location of the sensor flexible circuit and its
attachment to a wire connection to a display.
FIG. 4 is a bottom pictorial diagram of the stage of FIG. 2
depicting location of the sensor flexible circuit and its
attachment to a wireless connection to a display.
FIG. 5 is a first exploded diagram of the stage of FIG. 2 depicting
geometry of the sensor and sensor housing.
FIG. 6 is a second exploded diagram of the stage of FIG. 2 that
highlights the contour of the flexible circuit and sensor location
relative to other parts of the stage.
FIG. 7 is a pictorial diagram of the flexible circuit placement in
the stage body.
FIG. 8 is a pictorial diagram of the lead screw with magnet and
magnet cup.
FIG. 9 is a pictorial diagram of the magnet and sensor
geometry.
DETAILED DESCRIPTION
Shown in FIG. 1 is a prior art manual micro positioning stage 1
less than a few inches in longitudinal dimension. The stage 1
comprises a stage body 3, precision rails 5, 7, a slider 9 with
flexures 11 to preload the slider 9 against the reference rail 7, a
return spring 13 captivated between the slider 9 and stage body 3,
a lead screw 15 that may be manually advanced through a thread 17
in the stage body 3 to make contact with the slider 9 by rotation
of the thumb knob 19. Such a stage is capable of submicron motion.
The ability to provide accurate digital display of the position of
the stage slider is a valuable feature provided in the present
disclosure.
The device of FIG. 2 portrays a manually-actuated micro positioning
stage 21 that incorporates a mechanism for measurement and
electronic output of the slider position. A magnetic Hall Effect
sensor device is used to sense rotary position of the lead screw.
Based on the lead screw pitch, processor means converts the sensor
output into measurement and display of the lead screw and hence
slider displacement. A cap 25 contains a small disc magnet that is
poled diametrically and is affixed to the end of the lead screw in
contact with the slider 9 by means of a sensor housing 23. A Hall
Effect sensor (not shown in this figure) contained in a surface
mount electronic package is enclosed in the sensor housing 23 and
is positioned coaxially with the lead screw 15 in proximity to the
magnet-containing cap 25. Both the cap 25 and sensor housing 23 are
constructed of relatively hard materials to provide a functional
contact interface that supports smooth rotary motion of the lead
screw 15. Additionally, the cap 25 and sensor housing 23 material
compositions must be relatively non-magnetic and magnetically
permeable so as to not hinder or distort the magnetic field of the
magnet; brass is one alloy that would be acceptable, for example.
The use of field tailoring techniques such as the employment of
high magnetic permeability materials is within the scope of this
invention. The sensor is mounted on a flexible circuit 41 that is
routed underneath the slider 9 along the perimeter of the through
way 39 in the stage body 3 (as depicted in FIG. 3). As the lead
screw 15 is rotated, the magnetic field associated with magnetic
sweeps across the Hall Effect sensor device. An electronic output
indicative of the magnitude of angular motion is conveyed from the
sensor by way of the flexible circuit 41 to a wired connection 29
to remote display device 31. Contained in the display device is a
processor that performs signal conditioning and converts the sensed
angle data to linear displacement (based on lead screw pitch) for
display on a contained electronic display device 33, which may be
LED, LCD, or other display technologies well known in the prior
art. Buttons 35 and 37 permit the user to re-zero the position of
the sensor or convert the display units from metric to English,
respectively. The display device may be battery-powered or utilize
a wall plug adapter, has provision for concurrent display of
position data from multiple stages (as may be desired for x-y-z
configurations of stages), and stores last position for recall in
case power is lost.
In FIG. 3, it can be appreciated that the flexible circuit 41 is
seated along the perimeter of the through way 39 in the stage body
3 underneath the slider 9. The flexible circuit 41 can be
adhesively bound to the perimeter of the through way 39 for a
portion of its length in order to stress relieve it, to insure
compliance with the geometry as the stage body 3 and to permit a
portion of the flexible circuit to flex with motion of the slider
9. The terminal end of the flexible circuit 41 is electrically in
contact with an external wired connection 29 to the display device
and is affixed and stress relieved at this interface by a potted
volume 43 or other appropriate means.
An alternative to a wired connection 29 to electronic display
device 33 is shown in the Bluetooth (or other wireless technology)
connection of FIG. 4. The flexible circuit 41 connects with a
compact rechargeable battery 36 such as one or more lithium polymer
cells and to a Bluetooth transceiver chip enclosed in volume 34.
The Bluetooth transceiver is connected to an antenna applique 38
which isolates the antenna electrically from the stage body 3 and
thereby mitigates antenna pattern disturbance. The applique can be
conformal with the stage body. Various antenna alternatives, as
well known in the prior art, may be employed, for example, trailing
wire, or a low profile, surface mount type, ceramic loop antennas
(from such sources as Taoglas in Ireland), etc. Not shown in the
figures is the corresponding Bluetooth transceiver present in the
display device 33 with the attending antenna connection for this
embodiment.
In the exploded diagram of FIG. 5, it is visible that the sensor 45
is seated on one end of the flexible circuit 41 that is conformal
with the end of the slider 9 and it is coaxial with the lead screw
15. The shape of the flexible circuit 41 shown in FIG. 6 is
conformal with the through way 39 in the bottom of the stage. In
FIG. 7, the slider 9 and associated parts are absent to facilitate
a view the disposition of the flexible circuit from the bottom of
the stage. The magnet 51 is captivated in the cup 25 which is
inserted into the lead screw 15 as shown in FIG. 8. Alternative
means of affixing the cup 25 are envisioned including a
double-ended cap which permits insertion of the magnet 51 on one
end and insertion of the lead screw 15 on the other end. The magnet
51 is diametrically poled as depicted in FIG. 9 so that highest
flux density occurs on the edge of the magnet disc. Hence as the
magnet 51 is rotated, the circumferential inhomogeneity of the
field is sensed by the surface mount Hall Effect sensor 45. The
small magnet disc is of neodymium composition and a good candidate
for sensor 45 is the AS5600L part manufactured by Austria Micro
Systems. It provides 12 bits of resolution over 360 degrees of
rotation (0.0015 degrees of angular resolution). So when used in
concert with a lead screw pitch of 80 turns per inch, a theoretical
longitudinal motion resolution of 0.077 microns results. Of course,
error sources such as screw inaccuracies and other contributing
factors will detract from this ideal case, however, submicron
resolution and repeatable positioning are achievable.
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